1. Technical Field of the Invention
The present invention relates to an apparatus for applying visual effects to video signals, and a program for visual effect application. In particular, the present invention pertains to a video mixer apparatus for mixing video signals of multiple channels while applying a visual effect to each of the video signals to output a mixed video signal.
2. Prior Art
A video mixer apparatus mixes video signals of multiple input channels specified by a human operator of the video mixer apparatus to output a mixed video signal in real time. Upon this operation, the video mixer apparatus selects input channels, sets a mixing ratio among video signals of the multiple input channels, and sets a visual effect to be applied to each of the video signals of the respective input channels.
At the time of switching between input channels, the human operator may want to gradually change scenes from the preceding picture to the succeeding picture. A gradual change in brightness from the previous picture screen to the next picture screen is called a “crossfade.”
Such a gradual change may be made not only at the time of changing screens, but also anytime the human operator wants to vary a visual effect with time.
To obtain such a visual effect, the human operator of the video mixer apparatus manually adjusts controls or operators. However, since simultaneous operation of multiple operators is an error-prone operation, some skill is required to manipulate the operators. Further, since the operators are operated manually, it is difficult to repeat the same operation of the operators.
Especially when video signals inputted in real time need to be outputted in real time, quick manipulation of the controls is required and this makes it very difficult to make a sudden change in visual effect.
As is known in the art, for example, as disclosed in the following patent document 1, a video mixer apparatus having a function for recording and reproducing scene data is also known. The conventional video mixer apparatus can record setting states of multiple operators, which are set at certain timing on an operation panel in a memory device as a set of scene data, so that the setting states of the multiple operators on the operation panel at the recording time can be read out from the memory device at any later time to reproduce by a single operation the setting states of the multiple operators.
The above-mentioned scene data recording and reproducing function can be used to change visual effects automatically.
However, since the scene data is handled as a single unit, the current set of operational states is changed as a whole promptly at the time of switching, or over a certain period of time.
In other words, it does not allow for recording and reproducing a gradual change in visual effect in a period of transition during which the visual effect gradually varies.
The above mentioned patent document 1 is Japanese patent unexamined publication No. 2002-262179. The United States patent application corresponding to Japanese patent unexamined publication No. 2002-262179 is laid open as US-2002-0118302-A1.